1. Field of the Invention
The present general inventive concept relates to a controller chip and an image forming apparatus which perform color mis-registration correction and methods thereof, and more particularly, to a controller chip and an image forming apparatus which perform color mis-registration correction by analyzing edge of color image data and correcting software of the color image data and methods thereof.
2. Description of the Related Art
With the development of electronic technology, not only a computer but also various kinds of image forming apparatuses have been widely distributed.
An image forming apparatus refers to an apparatus which forms an image on various mediums such as a paper. Examples of image forming apparatuses include a printer, a copier, a scanner, a fax machine, and a multi-functional printer.
In the case of a printer, in recent years, more and more people use a laser printer which has better printing quality, printing speed, and less printing noise than a dot-matrix printer and an inkjet printer that have been widely used conventionally. A laser printer applies toner to a photo conductor using laser beam which is converted into a picture signal, transfers the toner applied to the photo conductor to a printing paper, and fuses the toner on the printing paper by high pressure and heat.
The laser printer prints an image through charging, writing, developing, transferring, and fusing. Charging represents a process of forming a negative (−) electric charge on the surface of a photo conductor as a result of Corona charging by applying high voltage (approximately 7000V) to a charging unit. Writing represents a process of forming a latent image by scanning a laser beam on the surface of the photo conductor where the negative (−) electric charge is formed, thereby extinguishing the negative (−) electric charge to form a shape, such as a letter, with the space that does not include the negative (−) charge. The portion of the photo conductor on which the negative (−) charge has been extinguished is a latent image. Developing is a process of attaching toner particles having a negative (−) charge to the latent image on the surface of the photo conductor. Transferring is a process of forming a positive (+) electric charge on the other side of a paper by applying a predetermined transfer voltage to a transferring unit while the paper is passing between the photo conductor and the transferring unit, thereby transferring the negative (−) toner particles on the surface of the photo conductor in the direction of the paper. Fusing is a process of applying heat and pressure to the paper to bond the toner particles to the paper. After going through the above processes, the image is formed on the paper and the paper is output from the printing device.
Recently, color laser printers have been developed to perform color printing using a laser printing method. Color laser printers use toners of four colors, that is, cyan (C), Magenta (M), Yellow (Y), and black (K), to reproduce a color image. In this case, four photo conductors are used to perform printing by each toner color in order to print a clear image.
In order to reproduce such a color image, toners should be overlapped with each other precisely on the same position using a plurality of photo conductors, developing units, and transferring units. However, as the number of printing papers increases, operation errors may occur between the developing units and the transferring units, causing the location of the toners to vary from their original position. Accordingly, color rids-registration may occur, blurring the edge of the color image. Conventionally, hardware fixes have been employed to correct such color mis-registration. That is, a test image is printed and the pattern of the test image is analyzed. Subsequently, color mis-registration is corrected by adjusting an operation time of a transferring unit and so forth based on the analysis. However, if this method is used, toners and papers are inevitably wasted.
Therefore, there is a need for technology to correct color mis-registration in more effective way.